These files are part of the dataset "Historical settlement first built layer (FBUY) for the U.S. 1810 � 2020 ,"contained in the dataverse �HISDAC-US: Historical Settlement Data Compilation for the United States� 
(https://dataverse.harvard.edu/dataverse/hisdacus).

Reference:
Ahn, Yoonjung;Leyk, Stefan;Uhl, Johannes H.; McShane, Caitlin M., 2023, "Gridded Settlement Data for the Conterminous United States Over 200 years", 
https://doi.org/10.7910/DVN/HHFM5E, Harvard Dataverse. 

Related Publication:
Leyk, Stefan; Uhl, Johannes H., 2018, "HISDAC-US: Historical Settlement Data Compilation for the Conterminous United States Over 200 Years," Scientific Data 5:180175
https://doi.org/10.1038/sdata.2018.175
Uhl, J. H. et al. Fine-grained, spatio-temporal datasets measuring 200 years of landdevelopment in the United States. Earth Syst. Sci. Data 96�114 (2020). doi:10.4324/9781315019444-13

This dataset contains the following files:

- FBUY.tiff: Archive that contains the FBUY (values indicates the presence of built structures built-year)
- NobuiltYear.tiff: Archive that contains the values indicates the presence of built structures without built year 

Abbreviations and explanations:
FBUY:		First built-up year. A raster composite with each pixel value indicating the year of first settlement within the pixel area.

Data source: 
- Zillow Transaction and Assessment Dataset (ZTRAX) (c) Zillow Inc.
- Parcel (c) Parcel Atlas
- BuildZero Open City Model
Spatial resolution: 250m
Coordinate reference system:
USA Contiguous Albers Equal Area Conic USGS version (EPSG:5070)
https://spatialreference.org/ref/sr-org/usa_contiguous_albers_equal_area_conic_usgs_version-2/
Proj4: +proj=aea +lat_1=29.5 +lat_2=45.5 +lat_0=23.0 +lon_0=-96 +x_0=0 +y_0=0 +ellps=GRS80 +datum=NAD83 +units=m +no_defs

Contact:
Stefan Leyk
Department of Geography
University of Colorado Boulder
GUGG 110, 260 UCB 
Boulder, CO 80309-0260, United States of America
stefan.leyk@colorado.edu